This invention relates to a stabilized absoption composition including a novel liquid absorbent for absorption type refrigerators, which absorbent is stable against the halogenated hydrocarbon type refrigerants in the absorption type refrigerators and also little corrosive on metals.
The mechanical compression type refrigerators have gained ground and spread widely since the 1940's with the improvement of working precision of the machines. Recently, however, in order to meet the growing request for utilization of solar heat or waste heat, attention is again being given to the absorption type refrigerators using a halogenated hydrocarbon type refrigerant.
Generally, in the absorption type refrigerators, a closed circuit containing an absorbent is adopted and a liquid halogenated hydrocarbon type refrigerant evaporates in an evaporator constituting a part of said circuit to drive out heat from the surrounding to thereby effect cooling. The vapor of said halogenated hydrocarbon type refrigerant contacts with and is absorbed into the low-concentration liquid absorbent in an absorber and the resultantly formed high-concentration absorbent is sent into a generator where said absorbent is heated by an external heat source to release vapor of the halogenated hydrocarbon type refrigerant. This vapor is condensed by a condenser and again flows into the evaporator. On the other hand, the low-concentration absorbent formed by releasing vapor of the halogenated hydrocarbon refrigerant again returns into the absorber and absorbs vapor of the halogenated hydrocarbon type refrigerant.
In such absorption type refrigerators where a halogenated hydrocarbon is used as refrigerant, use of a furan compound as an absorbent is proposed (U.S. Pat. No. 4,072,027). But the furan compounds are not suited for practical use as they are expensive and hardly available commercially. It is also proposed to use as absorbent a polyethylene glycol methyl ether type compound which has a very high absorbing capacity (Japanese Patent Appln. Kokai (Laid-Open) Nos. 55849/79 and 152257/79). However, when such polyethylene glycol methyl ether type compound is used as absorbent, there arises a problem of poor stability of the system wherein the halogenated hydrocarbon type refrigerant, a metal which forms a refrigerator and said absorbent coexist, and also a metal corroding reaction may occur as said absorbent contracts with Fe.sub.2 O.sub.3 formed on the surface of the surrounding iron type metal material during operation of the refrigerator. For example, when monochlorodifluoromethane is used as the halogenated hydrocarbon type refrigerant, the following reaction takes place: EQU 6CHClF.sub.2 +Fe.sub.2 O.sub.3 .fwdarw.3CHF.sub.3 +3CO+FeF.sub.3 +3HCl
As a result, iron halide is produced on the metal surface. There is also produced hydrogen chloride which is a corrosive element on the metal surface also promotes deterioration of the absorbent itself. This reaction is accelerated in the presence of water, and such a reaction also occurs when using other halogenated hydrocarbon type refrigerants. As for stabilizers for improving such metal corrosion, no report on studies has been made at present. Although the use of phosphite esters is disclosed in the above-mentioned U.S. Pat. No. 4,072,027 but said U.S. patent is quite silent on and gives no suggestion whether the phosphite esters are effective for a composition including a halogenated hydrocarbon as a refrigerant and an ethylene glycol series absorbent. The halogenated hydrocarbon type refrigerant to be used in this invention is of the type which has a boiling point of from -40.degree. to +25.degree. C., but when the absorption type refrigerator is operated by using as absorbent a polyethylene glycol methyl ether type compound of the general formula: CH.sub.3 --O--C.sub.2 H.sub.4 --O).sub.n R (I) (wherein n is an integer of 1 to 6, and R is H, CH.sub.3 -- or CH.sub.3 CO--), remarkable corrosion occurs on the metal surface of the generator. Therefore, establishment of certain anticorrosive means is essential for the practical use of said absorption type refrigerator for a long period of time.